1. Field of the Invention
This invention concerns a multi-needle stitched layer of nonbonded, polyethylene, plexifilamentary film-fibril strands, which forms a nonwoven fabric that is particularly useful as a wipe-cloth. The invention also concerns a process for making the nonwoven fabric.
2. Description of the Prior Art
Many types of woven and nonwoven materials have been used and suggested for use as a wipe-cloth (also sometimes called a "dust-cloth"). Superior wipe-cloths should possess several important characteristics. Such wipe-cloths should absorb or lift dust and oily films from a surface without leaving lint or a residue on the wiped surface. The cloths should be soft to prevent scratching of the surface being cleaned. Further, the cloths should have sufficient stability to permit thorough rubbing of the surface without linting or destruction of the cloth. Removed dust should be retained by the wipe-cloth and not drop off the cloth until the cloth is vigorously shaken. Some known dust-cloths are impregnated with an oily substance to assist in dust particle pickup and retention, but these often leave a residual film on the wiped surface.
Nonwoven sheets made from plexifilamentary strands of polyethylene film fibrils are known. Blades et al, U.S. Pat. No. 3,081,519, discloses, flash spinning of plexifilamentary strands of polyethylene film fibrils. Steuber, U.S. Pat. No. 3,169,899, discloses depositing such strands onto a moving receiver to form a nonwoven sheet. Methods of assembling strands deposited from a plurality of positions are disclosed by Knee, U.S. Pat. No. 3,402,227. Improved methods for depositing flash-spun plexifilamentary strands and forming them into sheets are disclosed by Pollock et al, U.S. Pat. No. 3,497,918. Bonded sheets are disclosed by David, U.S. Pat. No. 3,532,589.
The aforementioned methods have been used commercially in the manufacture of nonwoven sheet of polyethylene plexifilamentary strands. Sheet product, sold under the trademark "Tyvek" spunbonded polyolefin by E. I. du Pont de Nemours & Co., has been found useful in many applications. However, Applicant has found that when these sheets were tried for use as wipe cloths, the sheets were unsatisfactory. Such sheets in bonded form did not pick up or retain dust adequately. Nonbonded sheets did not have sufficient surface stability to permit any significant scrubbing or rubbing without destruction of the sheet surface.
Multi-needle stitching machines, generally known as "Arachne" or "Mali" machines (including Malimo, Malipol and Maliwatt machines) are known and have been used to insert stitches into a wide variety of fibrous substrates. Such machines and some of the fabrics produced therewith are disclosed by K. W. Bahlo, "New Fabrics Without Weaving", Papers of the American Association for Textile Technology, Inc., pp. 51-54 (November, 1965). Other disclosures of the use of such machines appear for example, in Ploch et al, U.S. Pat. No. 3,769,815, Hughes, U.S. Pat. No. 3,649,428 and Product Licensing Index, Research Disclosure, "Stitchbonded products of continuous filament nonwoven webs", p. 30 (June 1968). However, none of these disclosures concern stitching of sheets of polyethylene plexifilamentary film-fibril strands.
An object of the present invention is to provide a nonwoven fabric which overcomes the shortcomings associated with sheets of polyethylene plexifilamentary film-fibril strands and indeed provides a superior material for use as a wipe-cloth.